Functional organisation of the facial motor system in man

Author(s): Zidar, J.

Journal/Book: Collegium Antropol. 1998; 22: Inst Anthropological Res P O Box 290, Ulica Grada Vukovara 72/IV, 10000 Zagreb, Croatia. Collegium Antropologicum. 545-550.

Abstract: To investigate human corticobulbar projections, electromyographic responses from orbicularis oculi and orbicularis oris muscles were recorded in II healthy subjects after transcranial magnetic stimulation. Selective activation of lower facial motoneurones of one hemisphere was reached with the round coil 4 cm lateral to the vertex on, a line to the external auditory meatus with stimulus intensities from 45 to 55% (100% = 1.5 T). The mean latency of the OR muscle teas 11.5 +/- 1.77 ms contralaterally. Ipsilateral cortical responses were observed in 5 subjects (45%) at a mean latency of 13.88 +/- 2.17 ms. Corticobulbar innervation may have affected bilateral responses in the lower facial muscles as those persisted even after lidocaine blockade of both supraorbital nerves. The functional importance of ipsilateral projections to the lower facial muscles in man is lower than that of the contralateral projections,as evidenced by the fact that they cannot be observed in all subjects or in all motor units. The influence of the trigeminal sensory afferents was excluded from the study after blockade of both supraorbital nerves.

Note: Article Liscic RM, Inst Med Res & Occupat Hlth, 2 Ksaverska St, POB 291, Zagreb 10000, CROATIA

Keyword(s): MAGNETIC STIMULATION; UNIT RESPONSES; MUSCLES; ORGANIZATION; PROJECTIONS; MOTONEURONS; PATHWAYS; BRAIN

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